Integrator¶
L’intégrateur est l’algorithme de rendu utilisé pour calculer l’éclairage. cycles prend en charge actuellement un intégrateur de chemin avec un échantillonnage de lumière directe. Il fonctionne bien pour des configurations d’éclairage diverses, mais n’est pas aussi adapté pour les caustiques et quelques autres situations d’éclairage complexes.
Rays are traced from the camera into the scene, bouncing around until they find a light source such as a lamp, an object emitting light, or the world background. To find lamps and surfaces emitting light, both indirect light sampling (letting the ray follow the surface BSDF) and direct light sampling (picking a light source and tracing a ray towards it) are used.
Sampling¶
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- Sample Method
- il y a deux modes d’intégrateur qui peuvent être utilisés : Path Tracing et Branched Path Tracing.
- Square Samples
- Square the amount samples.
- Seed
Seed value for integrator to get different noise patterns.
- Animate Seed (clock icon)
- Ce bouton qui peut être trouvé sur le côté droit de la valeur Seed qui peut être utilisé pour donner différentes valeurs de graine (seed). C’est une bonne idée pour activer ceci pendant animation parce que dans le monde réel chaque trame a un motif de bruit différent.
- Clamp Direct
Cette option limite l’intensité maximale qu’un échantillon de rayons qui n’ont pas encore rebondi peuvent contribuer à un pixel. Il réduit le bruit au dépens de la précision. En mettant cette option à 0.0 désactive le ensemble.
Note
A common issue encountered with Path Tracing is the occurrence of « fireflies »: improbable samples that contribute very high values to pixels. This option provides a way to limit that. However, note that as you clamp out such values, other bright lights/reflections will be dimmed as well.
Care must be taken when using this setting to find a balance between mitigating fireflies and losing intentionally bright parts. It is often useful to clamp indirect bounces separately, as they tend to cause more fireflies than direct bounces. See the Clamp Indirect setting.
- Clamp Indirect
- La même chose que Clamp Direct, mais pour des rayons qui ont rebondi de multiples fois.
- Light Sampling Threshold
- Probabilistically terminates light samples when the light contribution is below this threshold (more noise but faster rendering). Zero disables the test and never ignores lights. This is useful because in large scenes with many light sources, some might only contribute a small amount to the final image, and increase render times. Using this setting can decrease the render times needed to calculate the rays which in the end have very little affect on the image.
- Pattern
Random sampling pattern used by the integrator.
- Sobol
- Uses a Sobol pattern to decide the random sampling pattern used by the integrator. See Sobol sequence on Wikipedia for more information.
- Correlated Multi-Jitter
- Uses a Correlated Multi-Jitter pattern to decide the random sampling pattern used by the integrator. See this Pixar paper for more information.
- Layer Samples
Quand des calques de rendu ont par nombre d’échantillon , cette option spécifie la manière de les utiliser.
- Use
- The render layer samples will override the set scene samples.
- Bounded
- Bound render layer samples by scene samples.
- Ignore
- Ignorer les réglages d’échantillon de calque de rendu.
Path Tracing¶
The Path Tracing integrator is a pure path tracer; at each hit it will bounce light in one direction and pick one light to receive lighting from. This makes each individual sample faster to compute, but will typically require more samples to clean up the noise.
- Render Samples
- Number of paths to trace for each pixel in the final render. As more samples are taken, the solution becomes less noisy and more accurate.
- Preview Samples
- Nombre d’échantillons pour le rendu de vue.
Branched Path Tracing¶
The non-progressive Branched Path Tracing integrator offers finer control over sampling. It is similar to Path Tracing, but at the first hit it will split the path for different surface components and will take all lights into account for shading instead of just one.
This makes each sample slower, but will reduce noise, especially in scenes dominated by direct or one-bounce lighting. To get the same number of diffuse samples as in the path tracing integrator, note that e.g. 250 path tracing samples = 10 AA samples x 25 diffuse samples. The Sampling panel shows this total number of samples.
- AA Render Samples
- Nombre d’échantillons à prendre pour chaque pixel dans le rendu final. Plus il y a d’échantillons plus cela va améliorer l’anti-aliasing.
- AA Preview Samples
- Nombre d’échantillons pour le rendu de vue.
- Diffuse Samples
- Nombre d’échantillons de rebond diffuse à prendre pour chaque échantillon AA.
- Glossy Samples
- Nombre d’échantillons de rebond à prendre pour chaque échantillon AA.
- Transmission Samples
- Nombre d’échantillons de rebond de *transformation *à prendre pour chaque échantillon AA.
- AO Samples
- nombre d’échantillons d’occlusion ambiante à prendre pour chaque échantillon AA.
- Mesh Light Samples
- Nombre d’échantillons de lumière de maillage à prendre pour chaque échantillon AA.
- Subsurface Samples
- Nombre d’échantillons de subsurface scattering à prendre pour chaque échantillon AA.
- Volume Samples
- Number of volume scattering samples to take for each AA sample.
- Sample All Direct Lights
- When enabled, Cycles will samples all lights in the scene for direct bounces, instead of randomly picking one. Disabling this can improve performance, when using a lot of AA Samples anyway, to clear up the render.
- Sample All Indirect Lights
- Similar to direct light, but for indirects lights. This can reduce noise in scenes with many lights.
Light Paths¶
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Bounces¶
- Max Bounces
- Maximum number of light bounces. For best quality, this should be set to the maximum. However, in practice, it may be good to set it to lower values for faster rendering. Setting it to maximum 0 bounces results in direct lighting only.
- Min Bounces
- Minimum number of light bounces for each path, after which the integrator uses Russian Roulette to terminate paths that contribute less to the image. Setting this higher gives less noise, but may also increase render time considerably. For a low number of bounces, it is strongly recommended to set this equal to the maximum number of bounces.
- Diffuse Bounces
- Maximum number of diffuse bounces.
- Glossy Bounces
- Maximum number of glossy bounces.
- Transmission Bounces
- Maximum number of transmission bounces.
- Volume Bounces
- Maximum number of volume scattering bounces.
Transparency¶
- Transparency Max
- Nombre maximal de rebonds de transparence.
- Transparency Min
- Minimum number of transparency bounces, after which Russian Roulette termination is used.
- Transparent Shadows
- For direct light sampling, use transparency of surfaces in between to produce shadows affected by transparency of those surfaces.
Caustics & Filter Glossy¶
- Reflective Caustics
- While in principle path tracing supports rendering of caustics with a sufficient number of samples, in practice it may be inefficient to the point that there is just too much noise. This option can be unchecked, to disable reflective caustics.
- Refractive Caustics
- La même chose que ci-dessu, mais pour les refractive caustics.
- Filter Glossy
When using a value higher than 0.0, this will blur glossy reflections after blurry bounces, to reduce noise at the cost of accuracy. 1.0 is a good starting value to tweak.
Some light paths have a low probability of being found while contributing much light to the pixel. As a result these light paths will be found in some pixels and not in others, causing fireflies. An example of such a difficult path might be a small light that is causing a small specular highlight on a sharp glossy material, which we are seeing through a rough glossy material. In fact in such a case we practically have a caustic.
With path tracing it is difficult to find the specular highlight, but if we increase the roughness on the material, the highlight gets bigger and softer, and so easier to find. Often this blurring will hardly be noticeable, because we are seeing it through a blurry material anyway, but there are also cases where this will lead to a loss of detail in lighting.
Voir aussi
See Reducing Noise for examples of the clamp settings in use.